Instrument transformer



Jan, 12 1926.

W. K. DICKINSON INSTRUMENT TRANSFORMER Filed August 14, 1925 m n e v .m

Wi lbur KDICKinSQI His Attorneg Patented J an. 12, 1926.

UNITED STATES PATENT comes.

WILBUB K. DICKINSON, OFLYNN; MASSACHUSETTS, ASSIGNOR, TO GENERAL ELEC- crnrc COMPANY, A conPonA'rroN on NEW 52031;.

INSTRUMENT TRANSF RMERQ Application filed August 14, 1925. SeriaI'Nc. 50,327.

To all whom it may concern:

Be it known that I, WILBUR K. Dioxin-v soN, a citizen of the United States, residing at Lynn, in the county of Essex, State of Massachusetts, have invented certain new and useful. Improvements in Instrument Transformers, of which the following is a specification. v

My invention relates to instrument transformers of the type in which a winding is mounted on a core which is separable to permit it to be opened and placed around a current carrying conductor. Such a transformer may be used for a variety of purposes but is commonly used in connection with an 'ammeter for measuring the current in the conductor which it surrounds. It s desirable that the contacting surfaces of the two-part core fit together accurately so that the reluctance of the flux path through the core may be low and it is the general ob ect of the invention to mount the core parts on their support so that their contacting surfaces may adjust themselves to an accurate fit when brought together. A further object of the invention is to mount the core parts on their support in such manner that the pressure between the contacting surfaces will be evenly distributed, thus further con-' tributing to low reluctance of the flux path and to a uniform distribution of the flux throughout the cross section of the path at the contacting surfaces between the two core parts.

Further objects and advantages will ap-.

ear from the following description taken in connection with the accompanying drawing in which Fig. 1 is a perspective view of an instrument transformer constructed in accordance with the invention, Fig. '2 is a side view of the transformer shown in Fig. 1. and Fig. 3 is a side View of a modified form of the invention, a section of the winding being broken away in Figs. 2 and 3 to reveal details of construction.

Like reference characters indicate similar parts in the different figures of the drawing.

In theform of the invention shown in Figs. 1 and 2 a closed substantially ring shaped core 10 is divided into two parts, thus forming two joints at opposite sides of the core. The contacting s'urlaces at these joints preferably lie in a single plane passing through the axis of the core. The

contacting surfaces at each joint are finished to fit together accurately. Each of the core parts comprises a stackof magnetic tended into the two spaces 13 inthe two parts of the core. The flattened end 16 of eachrhandle has an opening which fits the enlarged portion 12 of one'of the rivets 11 so that each core part is pivotally sup ported on the flattened end of the handle which carries it. The two-handles 14 are-crossed and pivoted together by a rivet 17 between the grips 15 and the flattened ends 16 so;

that the two parts of the core may be closed and pressed together by means ofthe grips 15. A clasp 18 may be used to hold the two core parts pressed tightly together while thetranformer is in use. A winding 19 is distributed in two parts over the two parts of the core and connected through a terminal box 20 with the outside leads 21.

A low reluctance path for-the magnetic flux in the core is desirable and for this .reason it is important that the contacting surfaces of the two core parts fit together accurately and it is also desirable that the pressure between the two core parts when closed together be distributed substantially equally-between the two joints. The surfaces ,at'the two core joints are accurately finished to make accurate contact when the.

two core parts are properly positioned together andlthe pivotal connections between the two core parts and the flattened ends 16 of the two handles permit proper relative adjustment of the two core parts -when pressedtogether by the handles. The particular rivet 11 which connects. each core part to its supportinug handle is preferably about midway between the two ends of the core part so that the pressure of the handle is disributed substantially equally between thetwo core joints.

v The construction shown in Fig. 3 is similar to that which has been described in connection with Figs. 1 and 2 except that the handles 14; are not crossed and are pivoted thereto.

The invention provides an efficient and convenient instrument transformer having a core which ma be easily opened and placed around a con uctor which cannot itself be conveniently opened. The pivotal connections between the core parts and their supporting handles permit these core parts to adjust themselves accurately together when pressed together by the handles and thus obviates the necessity of great accuracy in construction and compensates for wear in the pivotal connection between the two handles.

What I claim as new and. desire to secure by Letters Patent of the United States, is:

'a separable two part core and two pivotally connected handles supporting said core parts, one of'sad core parts being pivotally connected to its supporting handle.

21 An instrument transformer including a separabletwo part core, and two pivotally connected handles pivotally supporting said core parts.

3. An instrument transformer including'a separable two part laminated vcore, and two pivotally connected handles supporting said core parts, the lamination of one of said core parts being separated into two groups with a space therebetween, and one end of one of said handles extending into said space and being adjacent core part.

pivotally connected therein to the In witness whereof, I have hereunto set my hand this 11th day of August, 1925.

- WILBUR K. DICKINSON. 

